Demand from the mainland is driven by memories of a 2008 scandal over Chinese formula tainted with the industrial chemical melamine, which killed six children and affected more than 300,000 others.

Last year another domestic manufacturer's formula was found to be contaminated with carcinogens, despite official pledges to clean up the industry.

"We know that on the mainland food safety is a very serious problem," Ai Weiwei said.

"It largely related to a lack of supervision and moral decay within industry.

"Hong Kong people make profits from these problems, and are also victims.

Para Site art space is hosting the installation as part of a wider exhibition and has collaborated with Ai in the past.

Executive director Cosmin Costinas said all the cans of milk powder in the exhibit had been bought in Hong Kong.

In Australia, Chinese customers have been blamed for a shortage of formula in supermarkets and pharmacies, causing some outlets to ration sales, with limits also imposed in Europe after a run on baby milk powder.

Consumer research group Euromonitor says China is "by far" the world's largest market for formula.

A 2012 UNICEF report says breastfeeding rates in the country are low - just 28 per cent - due to time limits on maternity leave and aggressive marketing of formula.